Lifting-jack.



0. L. CRABB.

LIFTING JACK.

APPLICATION FILED NOY.17. 1911.

Patented Aug. 26,1913.

2 SHEETSSHEBT 1.

[miifon C. L. CRABB.

LIFTING JACK.

APPLICATION FILED NOV. 17, 1911.

1 ,07 1 ,21 3, Patented Aug. 26, 1913.

2 SHEETS-SHEET 2.

will 556 [ill/finial:

the parts in their lowered UNITED STATES PATENT OFFICE.

CHARLES L. CRABB, OF MILLINGTON, NEW JEBSEY, ASSIGNOB TO TOPP ING BROTHERS, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

LIF'IING-JACK.

Specification of Letters Patent.

Patented Aug. 26,1913.

To all whom it may concern Be it known that 1, CHARLES L. CRABB, a citizen of the United States, and resident of Millington, in the county of Morris and State of NewJersey, have invented a new and useful Improvement in LiftingJacks, of which the following is a specification.

This invention relates to an improvement in lifting jacks and has for its object to provide a device in which an oppositely threaded double lifting screw is rovided whereby each turn of the screw will lift the intermediate member of the jack a predetermined distance above the lower member or base. and, at the same time, will lift the up r member of the jack a predetermined istance with respect to the intermediate member thus lifting the upper member away from the lower member or base-a distance the sum of the movements of the intermediate and upper members.

A further object is to provide a jack of the above character which will be very simple in construction, easy to operate, strong and durable, and in which the operating parts are completely inclosed and protected in all positions of the jack.

A practical embodiment of my invention is represented in the accompanying drawin s, in -which igure 1 represents the lifting jack in to plan, Fig. 2 is a side view of the same wit osition, Fig. 3 is a section taken in the p ane of the line A-A of Fig. 2, looking in the direction of the arrows, Fig. 4 is a transverse section taken in the plane of the line BB of Fig. 3, looking in the direction of the arrows, and Fig. 5 is a section similar to Fig. 3, with the intermediate and upper members raised a distaiice away from the lower memher or base.

The lower member or base of the jack is denoted by 1, the intermediate member by 2 and the upper member by 3. These three members are hollow and are arranged to telescope one within the other. The lower member 1 is provided with a nut 4 arranged to receive the lower screw threaded portion 5 of an oppositely threaded double screw 6.

A bevel gear 7 is locked to the central portion of the double screw 6 within the u per ortion of the intermediate member 2 o the 1ack, in the present instance by providing a pin 9 passing through the screw and the hub of the said gear. This bevel gear 7 is plished 1n the provided with a shoulder 10 between which and the removable top 11 of the intermediate member 2 is interposed an antifriction bearing 8, for eliminating friction as far as possible at this point.

A horizontal shaft 12 is provided with a bevel gear 13 which meshes with the bevel gear 7 within the intermediate member 2.

This shaft 12 is mounted in suitable bear- ,ings in a plate 14 secured to the intermediate member 2.

A crank handle, not shown herein, or any other device, may be attached to the shaft 12 i for rotating the same to raise and lower the jack.

The upper portion 15 of the double screw 6 is threaded oppositely from the lower portion 5. This upper screw threaded portion 15 engages the travelingnut 17, which nut is provided with oppositely arranged lugs 18,

19, located inrecesses 20, 21, in the inner walls of the upper member 3 for preventing the nut from turning.

Anti-friction bearings are interposed between the upper member and the traveling nut, as follows :An annular row of balls 22 is interposed between upper and intermediate bearing plates 24, 25, and another annular row of balls 23 is interposed between the intermediate and lower bearing plates 25, 16. The intermediate bearing plate 25 is made to turn with the double screw 6 so as to insure a rolling action of the balls between the upper, lower and intermediate bearing plates, and thereby distribute the load evenly on the traveling nut 17, so as to absolutely prevent the nut from cramping on the screw 6. This is accomresent instance by cutting away the opposite sides of the upper screw threaded portion 15 and forming the hole through the intermediate bearing plate 25 to loosely fit the cross sectional form of the cutaway portion of the screw; the upper and lower bearing plates being, the one pinned to the upper member, and the other to the traveling nut.

The upper member 3 of the jack is provided with a shoulder 26 having an extended engagement with the upper bearing plate 24 so as to give great strength and rigidity to the jack when in its raised position.

The upper member 3 is cut away along one side to permit its movement relative to the intermediate member 2 and a shield 27 uprises from the top 11 of the intermediate member in position to close the 0 ening which would: otherwise be formed y the separation of the upper and intermediate members.

A screw 28 serves as a stop to prevent the upper member 3 from being separated unintentionally from the traveling nut 7 and another screw 29 is carried by the upper member in position to engage a shoulder or abutment 30 on the intermediate member to serve as a stop for limiting the movement of the upper member away from the intermediate and prevent the entire separation of the three members.

Oil is supplied to the screw threaded connections between the several parts, by providing a longitudinal duct 31 leading downwardly from the top of the screw, said duct having outlets where the screw passes through the nut 4 and the traveling nut 17. This duct may be packed with a wick so as to feed the oil in small quantities only.

In operation, as the oppositely threaded double screw 6 is turned by the rotation of the shaft 12 to lift the jack, the intermediate member 2 will be lifted a certain distance with respect to the lower member 1 by the engagement of the lower screw threaded portion 5 with the nut 4. At the same time, the upper member 3 will be lifted a proportionate distance with respect to the intermediate member 2 by the engagement of the upper screw threaded portion 15 with the traveling nut 17. Therefore, the total lifting of the upper member 3 will be the sum of the distances traveled by the intermediate member and the upper member.

It is evident that various changes might be resorted to in the construction, form and arrangement of the several parts without departing from the spirit and scope of my invention; hence I do not wish to limit myself strictly to the structure herein set forth, but

What I claim is 1. A lifting jack comprising telescoping upper, lower and intermediate members and an oppositely threaded double screw carrying the intermediate member, having its oppositely threaded portions engaged with the upper and lower members, respectively, said upper member having a cutaway portion, and a shield on the intermediate member for said cutaway portion.

2. A lifting jack comprising telescoping upper, lower and intermediate members, an oppositely threaded double screw carrying the intermediate member, having its oppositely threaded portions engaged with the upper and lower members, respectively, said upper member having a cutaway portion, means on the intermediate member projecting through the cutaway portion, and a shield on the intermediate member for said cutaway portion.

3. A lifting jack comprising telescoping upper, lower and intermediate members, and an inclosed oppositely threaded double screw supporting the intermediate and upper members and having its oppositely threaded portions engaged with the upper and lower members respectively, said upper member having a cutaway portion and said intermediate member having a shield therefor.

4. A lifting jack comprising telescoping upper, lower and intermediate members, a traveling nut interlocked with the upper member, an oppositely threaded double screw supporting the intermediate and upper members and having one of its threaded portions engaged with the lower member and its other threaded portion engaged with said traveling nut and an anti-friction bearing interposed between said upper member and traveling nut, said anti-friction bearing comprising upper, lower and intermediate plates and interposed rollers, said upper and lower plates being interlocked with the upper member and traveling nut respectively and said intermediate plate being locked to rotate with said screw.

In testimony that I claim the foregoing as my invention, I have signed my name in presence of two witnesses, this sixteenth day of November 1911.

CHARLES L. CRABB.

Witnesses:

F. GEORGE BARRY, HENRY C. THIEME. 

